rs1056836, also known as 4326C/G, Val432Leu or L432V, is a SNP in the cytochrome P450 1B1 (CYP1B1) gene. This gene is a member of the CYP1 gene family and one of the major enzymes involved in the hydroxylation of estrogens, a reaction likely to be relevant in hormonal carcinogenesis. [In dbSNP orientation, the (C) allele encodes the Leu; the (G) the Val.]

rs1056836 increases susceptibility to lung cancer among those who never smoked 2.7x times for (C:G) heterozygotes and 3.1x times for (G;G) homozygotes, based on a study of 160 US patients. [PMID 16051642]